Bypass Without Synchronization (P1260 = 3) - Siemens SINAMICS S120 Function Manual

Extended Functions
Bypass (vector)
4.25.3

Bypass without synchronization (p1260 = 3)

Description
When the motor is transferred to the line supply, contactor K1 is opened (after the
drive converter pulses have been inhibited); the system then waits for the motor
de-excitation time and then contactor K2 is closed so that the motor is directly con-
nected to the line supply.
Because the motor is not synchronized when it is connected to the line supply an
equalization current flows. This must be taken into account when designing the
protective equipment (refer to Fig. 4-33).
When the converter retrieves the motor from the line supply, initially contactor K2 is
opened, and after the excitation time has expired, contactor K1 is closed. The drive
converter then connects to the rotating motor and the motor is fed from the drive
converter.
In this case, contactor K2 must be designed/selected to be able to switch inductive
loads. Contactors K1 and K2 must be interlocked so that they cannot simulta-
neously close.
Network
Fig. 4-33
4-284
Converter
K1
M
~
Circuit example, bypass without synchronization
K2
Interlocked against
simultaneously closing
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition
Protective
device